Temperatures could climb even higher today.
Yesterday saw the hottest temperature ever recorded in the month of May - with the mercury reaching 28.6 degrees at Shannon Airport.
Met Éireann is forecasting highs of 29 or 30 degrees in parts of Munster and south Leinster this afternoon.
Large crowds enjoyed the hot weather at the Doon Shore in Lough Key, Boyle, yesterday.
Gerard McDermott runs the Morning Glory Café in Carrigallen, Co Leitrim - he says the good weather has been good for business:
Anyone heading out on the water is being reminded to stay safe and be mindful of the risks of cold water shock.
Water Safety Ireland's Deputy CEO, Roger Sweeney says jumping in can cause the body to go into shock within seconds: